1. Field of the Invention
This invention is directed to a safety system for clearing a switch of air-born pollution, and in particular to a system for keeping a railroad switch clear of snow, to promote its sage operation.
2. Description of the Prior Art
Extensive use is presently being made in railway systems located in snow belt areas such as the more northerly States of the United States and in Canada, of air blowing systems, for keeping track switches of rail systems clear of snow, deposited directly and by induced drafting from trains. Track switches comprise movable twin portions of rail track that can be laterally pivoted to guide the flanged wheels of rolling stock from one track to an adjacent track, enabling the diversion of a train or its component cars from one track to another.
Such systems are vulnerable to becoming inoperative, or defectively operable in the presence of snow deposits. Snow is readily deposited between the fixed rails and the adjacent, movable switch points rail portions.
These snow deposits can prevent the full, unrestricted motion of the switch points from one operative position to another operative position, with grave and dangerous consequences. Numerous examples exist of prior art switch point air-blowing arrangements, such as U.S. Pat. Nos: 2,898,062 Magnus, August 1959; 3,972,497 Ringer, August 1976; 4,081,161 Upright, March 1978; 4,671,475; Widmer, June 1987; 4,674,718 Bjorklund, June 1987; 4,695,017 Ringer et al, September 1987 The current state of prior art is exemplified in Ringer et al U.S. Pat. No. 4,695,017 (referred to below a "U.S. '017").
U.S. '017 shows a fan for providing a high velocity mass flow of amvient air, connected by way of rectangular-section metal conduits to first, second, and possibly third stage air blowing nozzles, to blow high belocity air substantially horizontally into the gap between the switch points nad the respective stock (main) rails, in sufficient mass and at a sufficiently high velocity to keep the switch clear of snow, deposited both naturally, and by train-generated turbulence. The systems are most generally operated continuously during the snow season.
The conduits extend transversely of the road bed, below the rails and between the rail ties, with nozzles extending upwardly from the conduits, projecting above the level of the cross ties of the track, to about the height of the switch rails.
In accordance with the relevant official technical specification for the former Canadian National Railway, CN-066-SM 1991 Edition, the conduits and nozzles of these systems are of galvanized sheet metal, each installtion generally requiring to be custom-built.
The nozzle and duct potions of these existing systems have been found to be prone to being accidentally damaged, from impacts against the upstanding nozzles by equipment dragging from passing trains, and by the operation or passage of track maintenance equipment, etc.
Damage occurring to the nozzles per se, which are sometimes torn away, frequently causes widespread damage to the connection conduits, the removal, repair and replacement of which is vary labour intensive and expensive, particularly in view of the custom-built aspect of their construction. Attempts to cope with this type of damage, by making the nozzles more robust and rigid, has been found in many instances to lead to increased consequential damage to the attached air conduits, with increased repair requirements. In instances of track maintenance, where the air blowing system requires temporary removal and replacement, a number of hours and considerable effort is usually required for removal and subsequent re-installation of the conduits and nozzles.
A further major disadvantage of these types of prior art systems is the use of galvanized metal conduit, located transversely below the stock rails, making electrical contact with the undersides of the stock rails. Normally, in most railways where air blower systems are installed, the stock rails are utilized as conductors for the control of track signal lights.
Accordingly, the respective portions of air conduit are connected by way of an electrical insulation break. The insulation, however, is prone to becoming contaminated, and electrically bridged. When this short circuit occurs, the system fails "safe", and the associated signal lights all go to the RED condition. This halts ass trains, causing a tremendous adverse impact upon the flow of rail traffic. Under these circumstances railroad regulations require, for each halted train, the obtaining of a written authorization to proceed under emergency conditions, and consequent passage across the affected zone of the track at 15-mile an hour, instead of being able to highball through, non-stop, at normal track speed for that section of the system.
Typically, for a 10-mile section of affected track, one train delayed 45-minutes will cost many thousands of dollars. With trains each averaging about 90-cars, extending about 5,000 feet, the economic losses associated with stopping, obtaining authorization to pass, and proceeding at reduced speed over the affected track zone, are very high.
As regards effecting temporary removal, of carrying out repairs on a damaged prior-art conduit-and-nozzle system, these may well be required in the depths of winter, possibly after dark, with minimal facilities and under semi-arctic conditions. In a worst-case scenario involving more than a nozzle, the conduit may have to be unbolted from the fan unit or from its output conduit an futher dis-assembled into its smaller component lengths by unbolting an array of bolts or capscrews at the flanged joints where necessary, to enable drawing of those portions from veneath the stock rails, for repair or replacement. This typically comprises a three-hour or more job for the repair person. The removal job may be further complicated by deformation or tearing of the conduit, from the initial, damaging impact against the nozzel.
A further major deficiency of existing, prior art systems, is an apparent total absence of provision to deep transverse track, actuator and indicator rods clear of snow. The transverse rods of a switch system comprise spacer rods connecting the two rail portions of the switch, to deep them parallel to each other, and actuator and indicator rads connecting the switch rails to the positioning mechanism, by which the switch is operated.
The complex structure of these rods, necessitated by the need to provide a wide range of adjustability, makes them vulnerable to jamming. Thus, the accumulation of snow, and/or consequential ice, about the transverse rods of a switch system can redily immobilize a switch against effective operation.
In summary, it can be readily appreciated that the currently used systems are highly prone to damage, and suffer from further major disadvantages, with the potential liability of becoming inoperable; of partially disabling the railway system, and of being difficult to service and to repair.